The objectives of this grant proposal are (1) to map, using serological techniques, the topographical arrangement of alloantigens on the cell surface of the mouse thymocyte and peripheral T lymphocyte, and (2) to investigate the induced rearrangement of these alloantigens called supramolecular "repatterning" which is triggered by binding of an appropriate antibody to an alloantigenic site or, in the case of H-Y, by the hormone, testosterone. We will initially study the physical interrelationships between the mouse alloantigens H-2D, H-2K, H-2L, Lyt-1, Lyt-2, Ly-5, TL, Thy-1, and Qa-2, and determine whether the relative positions of these cell surface components can be altered by binding with antibody. We will also determine whether such agents as colchicine and Cytochalasin B will inhibit alloantigenic repatterning. Finally, we will determine whether other agents besides antibody and testosterone will induce specific cell surface repatterning. Some genetic studies will also be performed. Methods to be used include the dual blocking assay, radio- or enzyme-immunoassays, antiserum production, hybridoma formation, cytotoxicity testing, and absorption procedures.